Acoustic echo cancellation (AEC) is used in telecommunications devices to improve audio quality. In this environment, an echo is a delayed reoccurrence of an original signal in a received or retransmitted signal. Audio echo may be caused by an acoustic echo path between the microphone and speaker of a communications device such as a telephone handset. AEC is particularly useful in so-called “hands-free” communications devices, where there is very little acoustic isolation between the microphone and speaker of the device.